Exodus 24:4

24:4 and Moses wrote down all the words of the Lord. Early in the morning he built an altar at the foot of the mountain and arranged twelve standing stones – according to the twelve tribes of Israel.

Exodus 24:7

24:7 He took the Book of the Covenant and read it aloud to the people, and they said, “We are willing to do and obey all that the Lord has spoken.”